1. Field of the invention
This invention relates to a force sensor of the kind that comprises a resonator having a frequency which varies with the intensity of the force having to be measured and including an oscillatory bar, and a pair of anchor members that are rigidly connected each to a corresponding end portion of the bar and which serve to apply the force having to be measured to the bar.
2. Prior art
Such a sensor is for instance described in U.S. Pat. No. 4,372,173. In this patent, the resonator is made of a thin plate of quartz that is photochemically manufactured and having the shape of either a bar or a double tuning fork. The advantage of this kind of resonator is that it has a high quality factor and great sensitivity to the application of a force. Accuarate measurments can as a result be made. Moreover, since the information associated with the frequency of the resonator is processed by an electronic circuit, it can be supplied in digital rather than analogical form, a feature that has many advantages. Unfortunately, because use is made of a quartz resonator, the sensor tends to be rather delicate, which is why, to this day, such a sensor has primarily been used in a laboratory environment.